Preparation of aromatic orthodinitriles



Patented Oct. 23,, 1945 1 1 t 2 OFFICE.

H W t 2,387,435.

. ranmnn riomor ARoMAimconTHm murmurs; Maurice ll. Fl'eyslicr; Buifalo;Y., assignor-to- Allied cliemical '&--Dye Corporation, acoi-poration-ofiNewYorke No Drawing App icatibmmnem,,1939,

serialino. 279x151:

193Glaiinsi (01.2607-465');

Thisiinvention relates; tow-a process ion the.oxychloridc-ipen-Inclofphthalcdiamideatatein:

ip'reparationofaromatictortho-dinitriles.from thewperaturenotexceeding165'C;,and"not exceedjcorresponding. diam-ides.Theinventionlrelates ing1135f C. forany consid rablepe ime. particularlyto the preparation .of'ortho-dinitrilesl inE a liquid reaction. med uefi m gi ll. of th ei benzene. series,, such.ias. orthorphthalodieorganic tert ary, base orthor-p tha i rilc. 5 nitrilefrom.thelcorresponding diamides; I producedfeconomi a ly n 8 d yi nAhmbjectloithepresent inyentiontisto furnishwithout.sulistantialiiormation i heterocyclicdean eiiicient,=economicall and practical method. of. rivativesr Thisresult issurprising in ViBW of' the producing aromaticortlio-dinit'riles.ingoodyield. fact,that diamides of aromaticortho-dicarboxand' in substantially pure. form. 10; ylic acidstend toformstable heterocyclic deriva it Another objectil of the presentinvention. is to. tivesusuch asphthalimide and imino-phthalimb phoyide amethodl 0t producing. ortho-phthalodie dine, under the, influence ofstrong dehydrating nitri le tfrom. ortho-phthalic aci'dl diamide, which.agents.

iseconomical; simple'andlsafeto.operate The invention is illustrated bythe following Other objects oii theinyention will in part be Specificexamples. The parts are by weight and;

obvious andwilllin part. appear hereinafter. temperatures are indegreescentigrade.

According to the preseiitinvent'iori aromatic. Example, 1 -l"75, parts,-of phthalodiamide are orthoedinitriles" are formed by dehydrating. the.added'td'lfldiparts of substantially puredimethylcorresponding.diamidesfiwithphosphorusoxychlm aniline("settingpoin t=2'.33 to 2.412") in a. reaction ride in. a liquid.reaction. medium comprising an. pot equipped with av vent, an agitator,and with organic tertiary base. as an acid binding agent. heating. andcooling means. The resulting slurry The liquid reaction. medium. mayconsist of. the. is heated! with continuous. agitation to about 505"organic tertiary base. (or a mixture. at organic. terto. 55. While thetemperature is held withinthese tiary bases)" alone-o1: in admixturewith one or limits, I63 parts. of I P0613 are added during a;

more organic liquids which. are. inert toward the 25. period, of about ahalf hour. lhe temperature of reagents and the reaction products and.which the reaction mixture is raised to about 70 to 80,

are miscible with the tertiary organic base toand. maintained within,these limits byintermityi'el dltherewit'h mixtures which. are liquid at.thev tent heating. Within a half hour after the temreaction.temperatures. Ifthe tertiary organic perature firstreaches 70; a suddenspqntaneous base is a liquid at the reaction. temperatures, it rise intemperature occurs, followed by a similarly maybe used in sufficient,amount to act. as a liquid rapid. fall. The entire phenomenon generally.re-. medium". or diluent for the reaction. as well as an quiresaltogether less than a half hour. External acidbinding agent. Theinvention is particularly heating is discontinued during the spontanequsapplicable to the productionof ortho-dinitriles of temperature risewhich may reach a maximum the benzene series especiallyortho-phthalodinibetween 135 and 165?, and is resumed only whentril'eflfroin ortho-phthalic acid diamide; the temperature falls tobetween 70 and 80.

I have found, according to the present. inven- 1 The mixture is thenmaintained between 70 and not; that phosphorus oxychloride isaparticularly 80 until 3hours have elapsed from the time at advantageousdehydrating. agent for converting which 70 was first attained, prior tothe spontlie diamides of aromatic ortho dicagboxylic acids 40 taneousrise in temperature. "The mixture. is then to aromatic ortho-dinitriles.Thus, as compared cooled to about to and maintained .at'this withpliosgene, one dehydrating agent proposed temperature for 1.8 1 01 15.;h fld, ,0 between for such use, phosphorus oxychloride is a relaand foraperiod of oneehalf to one hour, tiyely non-volatile liquid which is freefrom the t then cooled to about. 25 Q1, a lower te per tl lqt extr metoxicity of phosgene, and hence can be 45 The reaction mass is pouredinto an agitated mixhandled readily and safely without taking extremeture of 1000 parts ice, 1000 parts water, and 350 precautionarymeasures. As compared with acetic parts of hydrochloric acid (spec, gr,--1.,18) or anhydride, another dehydrating agentproposedfor 185 parts of66 B. sulfuric acid. The resulting such use, it is much more efficientin that a much slurry is agitated for 2 hours in order to break up smaler quantity of phosphorus oxychloride is 60 the lumps, then filtered,and the filter cake is requireutoproduce an equal yield of thedinitrile. Washed with cold water untilthe, washings are no norexainple,Ihave found that by treating ortholonger acid Congo red. The filter cakeis dried.

fihthalicacid diamide (hereinafter referred to as in an Oven at 80. Themelting rpc nt O th m 0 f'phthalodi'amide) with phosphorus oxychlorideuctis between 136 and 138- It ma DE U 1 B/S in fan as small as'one molof phosphorus 55 sufihtor. further purified by re'orystallizing from andthe liberated base may then be removed by the usual methods, e. g.,decantation, steam distillation, etc.

Example 2.--A mixture of 1622 parts of di methyl-aniline, dried overanhydrous sodium sul fate, and 403 parts of phthalodiamide is made in adry vessel and is heated to Tothis agitated mixture 377 parts of P0013are addedduring a period of from 2 to 3 hours, while the temperature ofthe reacting mass is maintained at 50i5 by.

means of controlled cooling. When all of the POC13 has been added, thetemperature of the continuously agitated mixture is gradually raised,during a period of about 2 hours to about to and is maintained withinthis temperature range for about 1 hour by heating or cooling asrequired. The mixture is then cooled to about 50 and agitated at thistemperature for from ,15 to 18 hours, The reaction mixture isthen pouredas a thin stream into an agitated mixture of 1950 parts of crushed ice,750 parts of 20 B. muriatic acid and 1950 parts of water. The finaltemperature is generally between 17 and 23. Agitation is continued inorder to break up the lumps. The slurry is then filtered, and the filtercake is washed several times with small quantities of cold water untilthe filtrate is nearly colorless, and no longer shows an acid reactionto Congo red. The filter cake is then dried in an oven at A fluify,yellowish, crystalline product results which melts at about 136. A highyield is obtained.

Dimethylaniline may be recovered from the filtrate by the proceduredisclosed in Example 1.

Example 3.-The same procedure is followed as in Example 2 except that,instead of employing the temperature conditions of Example 2, thereagents are mixed and agitated at from 20 to 30 for 64 hours. Thereaction mixture is then poured into an acid-ice mixture, as in Example2, and the phthalonitrile is recovered in a similar manner.

Example 4.A similar procedure to that of Example 2 is followed, exceptthat the phosphorus oxychloride is added while the reaction mixture ismaintained between and The mixture is held within this temperature rangefor 2 hours and is then heated at 135 for 4 hours. Thereafter themixture is cooled and the product is isolated as in Example 2. Thisprocedure gives a substantial saving in time of reaction. However, i

exothermic decomposition sometimes occurs at the relatively hightemperatures of this example, resulting in charring and decreasedyields. The procedure of this example is therefore somewhatlessdesirable than the procedures of Examples 1, 2 and 3.

Substantially the same results are obtained in the procedure of Example4 if dimethylaniline is replaced by an approximately equimolecularquantity of tri-n-butylamine.

It will be realized by those skilled in the art that the invention isnot limited to the details disclosed in the above specific examples, andthat changes can be made without departing from the scope of theinvention.

Thus, the process of the present invention may be used in general forthe conversion of substi tuted or unsubstituted diamides of aromaticortho-dicarboxylic acids to the corresponding dinitriles; for instance,those of the benzene,

vention, at least 4 molecular equivalents, and preferablyfromb to 6equivalents, of the organic tertiary base are employed per mol of POClsin order to bind or neutralize all of the acids produced in thereaction.Lower proportions of the base cause lowering of the yield; greaterproportions may be used, but merely increase the cost of the process.

, While the organic tertiary base is preferably used alone as a mediumfor the reaction, inert organic liquids which are miscible with the saidbase also may be present in the reaction mixture. In order to maintainthe reaction mixture substantially in s the liquid phase, the mixture ofthe organic tertiary base with the inert organic diluent-or the organictertiary base itself if used alonemust be liquid at the temperaturesemployed in the reaction, and is preferably a solvent for the reagentsand products of the reaction. In order to maintain the reaction masssufficiently fluid and dilute, at least 4 parts by weight of the organictertiary base, or of its mixture with an inert organic solvent, arepreferably employed per part by weight of the ortho-arornatic diamide. I

Theterm, organic tertiary base. is used herein'to designate tertiaryaminesof the aliphatic, cycloaliphatic, and aromatic series, andheterocyclic bases in which a tertiary nitrogen atom is a part of theheterocyclic' ring. In the process of the present invention, tertiaryamines are preferably employed which bind or neutralize the acidsgenerated in the reaction but which are otherwise substantiallyunreactive. In order to avoid considerably lowered yields, it ispreferred to .use tertiary amines which are substantially freefromsecondary amines. Suitable organic tertiary bases are, for instance,dimethylaniline, diethylaniline, dimethyl toluidine, dietl'iyltoluidine, tri-n-butylamine, pyridine, and quinoline- Inert organicdiluents which may be used in conjunction with the organic tertiarybases are, for example, benzene, chloro-benzene, nitrobenzene, toluene,and kerosene.

Theamount of phosphorus oxychloride employed "may be varied. In thepreferred practice of the invention about 1 mol of phosphorusoxychloride is used for each mol of the ortho-aro.- matic diamide. agreater amount of phosphorus oxychloride may be used, although it isgenerallyv unnecessary and wasteful, requiring a corresponding excess ofthe organic tertiary base. While lesser amounts of phosphorusoxychloride also maybe used, any substantial reduction in the aforesaidpreferred proportions will result in considerably lowered yields.Proportions lower, than 0,8 mol of phosphorus oxychloride for each molof ortho-aromatic diamide are generally unsatisfactory. a

In general, satisfactory results are obtained if the phosphorusoxychloride is added slowly toian. agitated mixture of theortho-aromatic diamide and the organic tertiary bas'ewhile maintainingthe temperature between 20 and 110 C, The addition of phosphorusoxychloride to the mixture at temperatures above C. ordinarily reactionis ailowed to proceed to" ih etempe ai ea it i. sw etie-W re m iim i ater-7t s lia leoi t hi de retesemximhi aa iaiineihe s ic im 1 h ismamtained to bnngi 165, C Q attained for when t r n r n a v] QQIYL :remedtwhms h tem era ur a ie nj to the desired level. The spontaneous risein mm ture e avo de ib sn tet n cenirio led ep i aiasn llils rate iie 2-s m ic iw tancnei q an iimi e aoii te i lts m" nek tu hei en 5Q? his, se it h ar -s t ieqto utreeuir ia c rres on -i onelier-Per odic: mim l tn b e m e. new fi-l m e etu es a hieh...as 3, 53 Qwmay e,

radi n; f int mast es il t in xothermic. ide ma position andcorrespondinglylowered yields and ntam ni to vt e product a H r. ,4,- Uater the r c -male c nmlet d n t il c n be ward a s ab m1:

1Qwi e---w nrwedute rfoi t e allo r-examp s, nam d rii e er c i n mxture ner-mix: tu tle e w a dim ralta i suf cie t.

rong i wralv a idish uld be s, o;neui l e manecessa'ry i thacteto;anymppreciableextentwith the-aromatic dinitril e. Such acids maybeiforiexample, ,hy-

dronchloriclacid, iphosphoricuacid iort sulfuric. acid.

Whi e a ,i ons en bl re e sof the, miner acid m yheiemp oyedainthedrownin isolution, sufiicient water ispreierably used to prevent the.mineral acid normality from exceedingawalue'01.2.0;

and-@the temperature of; the drowned mixture -.is

reierablyfnotl ermitted to exceed .25; C. tolany substantialuextent,since mineral, acid solutions at, higherconcentrationsManditemperatunes. tend uid, may be separated as a filtercake by filtration, washed with cold water, and dried.

The dinitrile produced is in a good state of purity. It may be furtherpurified in any suitable way; as by distillation in steam or in vacuo,

or by recrystallization from hot water or from a suitable organicsolvent (for example, benzene,

chlorbenzene, nitrobenzene, alcohol, or glacial acetic acid).

qusnport ion o f the resulting, mixture, which 0 mp isinc a .fic i iii,aro "atiic a sin an amount. atieastsumci'efit' to centralize t e acids,formed in thereactidn. Y t 4 Aprocesaofprjoducihg' anaromatic or 32. wch corripriss reacting the] corre -l spending diamidevilithglfihdsbhorus oxychlqriide at] reaction lrlfiedium comprising, atertiar' f hetrocycient to neutralize the acids formed in the reactiOfllat a ,ternperature hot higher C irivfl iii ea iee me ium: ee r sine a eii i i aliphatic ami'ne in ,an amount at. least sufiicient toneutralizenthe acids formed in the reaction. in V A r ce s" of ler c unn n r fi TQ t'halQ '1 nitrile which comprises reacting prtho-phthalic ad am e 12 DhQ D 01 v xychlo le n. liquidreaction medium comprising anorganic tertiary basemi, n 1 i A r s; Qfnep n p r h odmia tril hi 'cpmri ssli a ii ".qrthq-nhthe iq. a d d smiss wi ;ph or s weh d nthc DreBnQ of a li id re c o m diumc i isin an inorganic tertiary; base in, anamount at least sufficient to neutralize the acids formed in the rep .YM; "a an nd: tide-A proc sor p och m av hcrp tha di nit-rile whichcomprises reacting OrthQrDhthfiliQ acid diamide With phosphorusoxychloride at a temperature not higher than 165 C. in the presence of aliquid reaction medium comprising an organic tertiary base in an amountat least sufficient to neutralize the acids formed in the reaction.

9. A process of producing ortho-phthalodinitrile which comprisesreacting ortho-phthalic paratedifro m the nonaqueous portion aciddiamide with at least 0.8 mol of phosphorus oxychloride for each mol ofthe diamide at a temperature not higher than 165 C in the presence of aliquid reaction medium comprising an organic tertiarybase in an amountat least sufii cient to neutralize the acids action. 7

10. A process of producing ortho-phthalodinitrile which comprisesreacting ortho-phthalic acid diamide with at least 0.8 mol of phosphorusoxychloride for each mol of the diamide at a temperature which does'notexceed 165 C., and which does not exceed 135 C. for a periodsubstantially longer than a half hour, in the presence of, a liquidreaction medium comprising an organic tertiary base in an amountat-least sulficient to neutralize the acids formed in the reac tion.

11. A process of producing ortho-phthalodinitrile which comprises addingat least 0.8 mol of phosphorus oxychloride to a mixture of one mol ofortho-phthalic acid diamide and a liquid reaction medium comprising anamount of an organic tertiary base at least suflicient to neutralize theacids formed in the resulting reaction, maintaining the temperature ofthe mixture below 120 C. during the addition of phosphorus oxychloride,and completing'the reaction by maintaining the resulting reactionmixture at a temperature which, for any considerable period of time,doesnot exceed 135 C.

12. A process of producing ortho-phthalodinitrile which comprises addingat least 0.8 mol of phosphorus oxychloride to a mixture of one mol ofortho-phthalic acid diamide and a liquid reaction medium comprising anamount of an organic tertiary base at least suflicient to neutralize theacids formed in the resulting reaction, maintaining the temperature ofthe mixture between 20 and 110 C. during the addition of the phosphorusoxychloride, and completing the reaction by maintaining the resultingreaction mixture at a temperature which, for any considerable period oftime, does not exceed 135 C.

13. A process of producing ortho-phthalodiniformed in the retrile whichcomprises adding at least 0.8 mol of phosphorus oxychloride to a mixtureof one mol of ortho-phthalic acid diamide and a liquid reaction mediumcomprising an amount of an organic tertiary base at least suflicient toneutralize phosphorus oxychloride to a mixture of one mol ofortho-phthalic acid diamide and a liquid reaction medium comprising anamount of a tertiary aromatic amine at least sufficient to neutralizethe acids formed in the resulting reaction, maintaining the temperatureof the mixture between 45 and 75 C. during the addition of thephosphorus oxychloride, and completing the reaction by maintaining theresulting reaction mixture at temperatures above 50 C., but notexceeding80 action medium comprising an amount of a tertiary heterocyclicnitrogenous base at least s'ufficient to neutralize the acids formed inthe re-' sulting reaction, maintaining the temperature of themixturebetween and 75 C. during the addition of the phosphorus oxychloride, andcompleting the reaction by maintaining the resulting reaction mixture attemperatures above C., but not exceeding 80 C. for any considerableperiod ofjtime. V 5 q 16. A process of producing ortho-phthalodinietrile which comprises adding at least 0.8 mol of phosphorus oxychlorideto a mixture of one mol of ortho-phthalic acid diamide and a liquidreaction medium comprising an amount of a tertiary aliphatic amine atleast sufficient to neutralize the acids formed in the resultingreaction, maintaining the temperature of the mixture be tween 45 and 75C. during the addition of'the phosphorus oxychloride, and completing thereaction by maintaining the resulting reaction mixture at temperaturesabove 50 (3., but not exceeding 80 C. for any. considerable period oftime.

17. A process of producing ortho-phthalodinitrile which comprises addingabout one mol of phosphorus oxychloride to a mixture of one mol ofortho-phthalic' acid diamide in admixture with dimethylaniline in anamount by Weight about 4 times the weight of the diamide, maintainingthe temperature of the mixture below 120 C; during the addition of thephosphorus oxychloride, and completing the reaction by maintaining theresulting reaction mixture at a temperature above 50 C., but notexceeding 135 C. for a period substantially longer than a half hour.

18. A process of producing ortho-phthalodinitrile which comprises addingabout one mol of phosphorus oxychloride to a mixture of one mol ofortho-phthalic acid diamide in admixture with dimethylaniline in anamount by weight about 4 times the weight of the diamide, maintainingthetemperature of the mixture between 20 and 110 C. during the addition ofthe'phosphorus oxychloride, and completing the reaction by maintainingthe resulting reaction mixture at a temperature below 135 C.

19. A process of producing ortho-phthalodinitrile which comprises addingabout onemol of phosphorus oxychloride to a mixture of one mol ofortho-phthalic acid diamide in admixture with dimethylaniline in anamount'by weight about 4 times the weight of the diamide, maintainingthe temperature of the mixture between 45and C. during the addition ofthe phosphorus oxychloride, and completing the reaction by maintainingthe resulting reaction mixture at a temperature above 50 C., but notexceeding C.-for a'period substantially longer than a half hour.

' MAURICE H. FLEYSHER

